Dental intra-oral X-ray images are taken by using an X-ray examination apparatus which typically include a multi-jointed arm construction and an X-ray source placed inside a housing. Typically, an elongated collimator limiting the X-ray beam has been attached or arranged to be attached to the housing. The imaging process includes placing the X-ray device in the proximity of the object area to be imaged and aiming the X-ray beam so that it will meet the sensor in a correct orientation and at a desired angle. Typically, the X-ray beam is arranged perpendicularly with respect to a film, or some other sensor placed inside the patient's mouth.
Dental professionals do generally recognize the problems which relate to aiming and orienting the X-ray beam concentrically as well as so that, for eliminating geometric distortions and unsharpness of the image, the X-ray beam is not inclined or turned with respect to the means for receiving image data. Thus, different aiming arrangements have been developed to facilitate correct positioning of the X-ray source with respect to the sensor. One approach according to prior art is to attach the X-ray source and the means for receiving image data such as a film, a phosphorous imaging plate, a CCD sensor or other digital sensor physically to each other for the duration of irradiation.
The junction assemblies designed for physical connection of imaging means typically include an aiming arm, which may be attached both to a sensor holder/bite block and to the housing of the X-ray source. The latter connection is typically made by means of an aiming ring attached to a collimator tube of the X-ray device housing. Since there are several imaging modes in intra-oral imaging, such as the left- and right-side anterior, posterior, endodontic and bitewing imaging, assemblies comprising components of special shapes are required for supporting these special imaging modes for enabling different sensor positions and aimings of the sensor with respect to the X-ray beam. Some prior-art systems and assemblies utilising this approach are presented in patent specifications U.S. Pat. Nos. 6,343,875 B1, 5,632,779 A, 4,507,798 A and 4,554,676 A.
However, many of the dental professionals find these systems, in which the sensor placed inside the mouth should be physically connected to the X-ray device, difficult to use in practice. A reason for this is, first, that if all connections of the assembly are made prior to positioning the sensor in the mouth, it has proven difficult to direct the entire relatively heavy construction, including an X-ray tube and its arm construction, to its proper and precisely correct position. Second, if the sensor is first placed in the correct position in the mouth, assembling the construction has proven difficult—that is, e.g. connecting the aiming arm to the X-ray device so that the connecting process would not cause movement of the sensor or discomfort to the patient.
Because of these practical problems related to the abovementioned operations, the technical advantages of these systems are frequently ignored and aiming is done by simply visually estimating the correct place and orientation of the X-ray device, possibly by using as a help the position and orientation of the aiming arm protruding from patient's mouth. One has also tried to utilise the thin aiming arm to facilitate aiming by connecting it manually e.g. to the outer surface of the collimator of the X-ray tube, with limited success, however. This is not the least because of the fact that it has proven quite difficult to keep the sensor in a correct position by keeping the thin aiming arm between one's fingers and, at the same time, direct the arm construction of the X-ray source, especially into contact with the thin aiming arm. The probability for a repeated success in achieving the same distance between the X-ray source and the image forming plane, not to mention the proper and precise orientation of the X-ray beam, is clearly not extremely high by these methods.
A further problem of prior-art aiming assemblies is that, because of the great number of different components required for supporting different intra oral imaging modes, a lot of experience or learning by trial-and-error is required in order to be able to assemble the jigsaw puzzle according to each imaging mode.